This invention relates to a rotary damper which damps relative rotation between a driven-to-rotate member and a fixed support member supporting this driven-to-rotate member to rotate freely, by viscosity resistance of a viscous fluid.
As the above-described rotary damper, for example, one that is constituted by a driven-to-rotate member which integrally has a driven-to-rotate part which couples to a drive member such as a gear or rack, a fixed support member which holds this driven-to-rotate member to rotate freely, an annular receiving part which is formed between this fixed support member and the driven-to-rotate member, a seal means which seals the outer perimeter of this receiving part so that the driven-to-rotate member and the fixed support member are capable of relative rotation, and a viscous fluid which is received inside the receiving part and damps relative rotation between the driven-to-rotate member and the fixed support member, is well known. See, for example, Japanese Patent No. 3421484.
The aforementioned conventional rotary damper, however, does not have a means for closing the inner perimeter of the receiving part during assembly, so that the viscous fluid will not leak while it is allowed to communicate with the atmosphere.
Accordingly, because of the accumulation of air in the conventional receiving part, the assembly characteristics become poor. In addition, air mixes into the viscous fluid and variation is caused in the torque, and the torque precision is no longer constant (i.e., torque irregularity is caused).
Accordingly, an object of the present invention is to eliminate undesirable characteristics those described above by providing a rotary damper which is easier to assemble by virtue of eliminating the accumulation of unwanted air inside the receiving part, and in which air no longer mixes into the viscous fluid so that the torque precision can be made constant.
Further objects and advantages of the invention will be apparent from the following description of the invention and the associated drawings.